The “userland” jailbreak vulnerability that is used as part of the Spirit jailbreak tool was not patched by Apple. @planetbeing and @chpwn was able to get root access to the iPhone 4 using code from @comex’s userland jailbreak method. However there won’t be a carrier unlock for the iPhone 4 anytime soon because the baseband runs on a different OS than previous models. This means that the ultrasn0w unlocking tool needs to be completely rewritten. And Joshua Hill said that the unlock won’t be released anytime soon because it contains some of Apple’s proprietary code.
Below is a quote as reported by Redmond Pie about the baseband differences:
The DevTeam and others have been checking through the iPhone 4, and have noticed the baseband runs a completely different OS than on previous models. The iPhone 3G and 3G[S] both ran Nucleus OS on the PMB8878 baseband CPU (aka XGold 608), where the iPhone 2G ran the PMB8876 (aka S-Gold 2). iPhone 4 uses the PMB9800, or X-Gold 618 ? running a separate OS ? ThreadX, an RTOS by ExpressLogic.
Think I’m the first one I know about to get a root shell (and SSH) on iPhone 4, using poor @comex’s code (since he has no iPhone 4).